Well-ordered trimeric HIV-1 subtype B and C soluble spike mimetics generated by negative selection display...

Area of Science:

• Immunology
• Structural Biology
• Virology

Background:

• Soluble mimics of the HIV-1 envelope glycoprotein (Env), such as BG505 gp140 SOSIP, are crucial for structure-based immunogen design.
• Previous efforts have faced challenges in obtaining homogeneous, well-ordered SOSIP trimers from diverse HIV-1 subtypes.
• Understanding the structural variations in Env trimers is key to developing effective vaccine candidates.

Purpose of the Study:

• To develop a method for purifying homogeneous, well-ordered SOSIP trimers from subtypes B and C HIV-1.
• To utilize non-broadly neutralizing antibodies (non-bNAbs) targeting the CD4 binding site (CD4bs) for negative selection.
• To characterize the structural and antigenic properties of the rescued trimers for potential vaccine applications.

Main Methods:

• Employed a negative-selection purification strategy using CD4bs non-bNAbs to remove disordered Env trimers.
• Utilized electron microscopy (EM) for structural analysis and 3D reconstruction of purified trimers.
• Applied bio-layer light interferometry (BLI) to assess antibody binding kinetics and specificity.

Main Results:

• Successfully rescued homogeneous, well-ordered subtype B and C SOSIP trimers from heterogeneous mixtures.
• 3D EM reconstructions revealed detailed structures of trimers in various states, including complexed with antibodies.
• BLI confirmed efficient recognition of purified trimers by broadly neutralizing antibodies (bNAbs) and poor recognition by non-bNAbs.

Conclusions:

• Non-bNAb-mediated negative selection is an effective strategy for isolating native-like, well-ordered Env trimers.
• The rescued subtype B and C SOSIP trimers serve as promising soluble mimics of the native viral spike.
• This method provides a new avenue for producing candidate vaccine immunogens from diverse HIV-1 subtypes.